1) Continuing our work on exosomes as a source of biomarkers, in collaboration with the Knepper group we found that Tamm-Horsfall protein complicates the purification of exosomes from humans and animals. We continue to work on methods to improve recovery of exosomal protein and miRNA in light of these observations. 2) Serum creatinine is used clinically as a biomarker for acute kidney injury, and in collaboration with the Schnermann/Briggs group we further demonstrate that in mice the extent of tubular secretion confounds the use of serum creatinine. We continue to work on alternatives to serum creatinine such as serum cystatin C.